The tiny ant Forelius pusillus makes its home in the sugar cane fields of Brazil. Each night, the ants seal up the entrance to their nest with sand, a defensive measure against marauding colonies of predatory army ants. Each night, a few workers die for the greater good.

In order to make sure the nest entrance is completely closed, a few Forelius pusillus workers must remain outside to pack down the last bits of sand. It's a kind of suicide mission. Unable to re-enter the nest, these ants are doomed to die from the night cold and wind, or be killed by predators.

The recent discovery of these sacrificial ants by an international team of researchers headed by Adam Tolfilski of the Agricultural University in Poland adds a new twist to the phenomenon of insect altruism.

There are many examples of insects sacrificing themselves for the good of the group, such as honeybees using their stingers to defend the hive and dying in the process. But the entrance-sealing activity of F. pusillus is the first recorded case of insects sacrificing themselves through a premeditated and pre-emptive act.

"The ants sacrifice their lives every evening even if the colony isn't under attack by predators," Tolfilski told New Scientist magazine.

VERBATIM

Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly 92 million miles is an utterly insignificant little blue-green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.

— Science fiction writer and humorist Douglas Adams (1952-2001)

BRAIN SWEAT

How long would it take you to count a billion dollars?

a) 32 hours

b) 32 days

c) 32 months

d) 32 years

QUIRKS OF NATURE

The deep-sea female anglerfish is many times larger than her mate. The male anchors himself atop the head of the female and remains there the rest of his life. In fact, they literally become one, eventually merging digestive and circulatory organs. All that ultimately remains of the male are two very large generative organs and a few fins.

BRAIN SWEAT ANSWER

d) 32 years. Or to be more precise: 31 years, 259 days, 1 hour, 46 minutes and 40 seconds, according to Eva Everything, author of "What Does the Moon Smell Like?"

Be happy we're talking about an American billion, which is one thousand million, and not a British billion (a million million). The latter would take almost 3,200 years to count, Everything writes.

JUST ASKING

Why do scientists call it research when they're searching for something new?

THERE'S A WORD FOR THAT

Chalaza — the structural fibers that anchor an egg yolk inside its shell.

OUR IGNOBEL HISTORY

Back in December, we reported on a major breakthrough by Douglas Smith, a University of California San Diego physicist, and research assistant Dorian Raymer: A mathematical explanation for why stringy things like Christmas lights and hair inevitably tangle.

Their achievement, which did not explain how to keep things from becoming tangled, has not gone unrewarded (perhaps much to their dismay).

Last week, they were awarded the 2008 Ig Nobel Prize in physics in a ceremony at Harvard University.

To find out more about Scott LaFee and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.